CN114026892A

CN114026892A - Communication device, infrastructure equipment and method

Info

Publication number: CN114026892A
Application number: CN202080047149.9A
Authority: CN
Inventors: 魏宇欣; 维韦克·夏尔马; 若林秀治; 亚辛·阿登·阿瓦德
Original assignee: Sony Group Corp
Current assignee: Sony Group Corp
Priority date: 2019-07-03
Filing date: 2020-06-10
Publication date: 2022-02-08
Also published as: US20220353761A1; WO2021001130A1; EP3973729A1

Abstract

A method of operating a first communications device to communicate with a second communications device, the method comprising: transmitting or receiving signals representing data to or from a second communication device over the wireless interface, the signals being transmitted or received by the second communication device according to the current configuration; determining that the current configuration is to be changed to a new configuration; sending a handover command to the second communication device over the wireless interface, the handover command including an indication that the new configuration replaces the current configuration; and receiving a handover rejection indication from the second communication device via the wireless interface, the handover rejection indication indicating to the first communication device that the second communication device is to continue operating according to the current configuration.

Description

Communication device, infrastructure equipment and method

Technical Field

The present disclosure relates to methods and apparatus for communicating signals between communication devices in a wireless communication system.

The present application claims priority from european patent application EP19184207.9, the entire contents of which are incorporated herein by reference.

Background

The "background" description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.

Mobile telecommunications systems, such as those based on the 3GPP defined UMTS and Long Term Evolution (LTE) architecture, are capable of supporting more sophisticated services than the simple voice and messaging services provided by previous generations of mobile telecommunications systems. For example, with the improved radio interface and enhanced data rates provided by LTE systems, users are able to enjoy high data rate applications (such as video streaming and video conferencing) on mobile communication devices that were previously only available over fixed line data connections.

Thus, the need to deploy mobile telecommunications networks is very strong and the coverage area of these networks, i.e. the geographical location where the network can be accessed via infrastructure equipment, is expected to increase rapidly.

However, there may still be limitations on network capacity and the geographic area that such networks may serve.

For example, these limitations may be particularly relevant where the network is experiencing high load and high data rate communications between communication devices, or when communications are required between communication devices but the communication devices may not be within the network infrastructure equipment coverage area.

In other cases, delays in transmitting data via network infrastructure equipment may be undesirable.

It has therefore been proposed that a communication device may communicate directly with another communication device in a peer-to-peer or device-to-device (D2D) manner, i.e. without the need to send data from one device to another via network infrastructure equipment.

However, this can present challenges when the radio link used to transmit the data is not suitable or becomes unsuitable.

Accordingly, there is a need for a handover procedure for use in peer-to-peer communications that can overcome some of these problems.

Disclosure of Invention

The present disclosure may help solve or alleviate at least some of the problems discussed above.

Various aspects and features of the disclosure are defined in the appended claims.

It is to be understood that both the foregoing general description and the following detailed description are exemplary, but are not restrictive, of the present technology. The described embodiments, together with further advantages, will be best understood by reference to the following detailed description taken in conjunction with the accompanying drawings.

Drawings

A more complete understanding of the present disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein like reference numbers designate identical or corresponding parts throughout the several views, and wherein:

fig. 1 schematically represents some aspects of an LTE-type wireless telecommunications system that may be configured to operate in accordance with certain embodiments of the present disclosure;

fig. 2 schematically represents some aspects of a new Radio Access Technology (RAT) wireless communication system that may be configured to operate in accordance with certain embodiments of the present disclosure;

FIG. 3 is a schematic block diagram of some components of the wireless communication system shown in FIG. 2 to illustrate an exemplary embodiment of the present technique in more detail;

fig. 4 is a ladder diagram representing some aspects of an exemplary wireless communication device handoff scenario that may be used in accordance with the wireless telecommunication systems shown in fig. 1 and 2;

fig. 5 schematically represents some aspects of a wireless telecommunications system in which at least two wireless communication devices are configured to communicate with each other via a sidelink connection;

FIG. 6 is a ladder diagram representing some aspects of a wireless communication device handoff scenario that may be used in accordance with an embodiment of the present disclosure;

FIG. 7 is a ladder diagram representing some aspects of a wireless communication device handoff scenario that may be used in accordance with an embodiment of the present disclosure; and

fig. 8 illustrates a message sequence chart showing handover in accordance with embodiments of the present technology.

Detailed Description

Long Term Evolution (LTE) wireless communication system

Fig. 1 provides a schematic diagram illustrating some basic functions of a mobile telecommunications network/system 100 operating generally in accordance with LTE principles, but which may also support other radio access technologies and may be adapted to implement embodiments of the present disclosure as described herein. Certain aspects of the various elements of fig. 1 and their respective modes of operation are well known and defined in relevant standards governed by the 3gpp (rtm) organization and are also described in many books on the subject (e.g., Holma h. and Toskala a [1 ]). It will be appreciated that operational aspects of the telecommunications network discussed herein that are not specifically described (e.g., with respect to specific communication protocols and physical channels for communicating between different elements) may be implemented in accordance with any known technique (e.g., in accordance with the relevant standard and known proposed modifications and additions to the relevant standard).

The network 100 comprises a plurality of base stations 101 connected to a core network portion 102. Each base station provides a coverage area 103 (e.g., a cell) within which data can be communicated with and from the communication device 104. Data is transmitted from the base station 101 via a radio downlink to the communication devices 104 within the respective coverage area 103. Data is transmitted from the communication device 104 to the base station 101 via a radio uplink. The core network portion 102 routes data to and from the communication device 104 via the respective base stations 101 and provides functions such as authentication, mobility management, charging, etc. A communication device may also be referred to as a mobile station, User Equipment (UE), user terminal, mobile radio, terminal device, etc. A base station as an example of a network infrastructure equipment/network access node may also be referred to as a transceiver station/nodeB/e-nodeB, g-nodeB (gnb), etc. In this regard, different terminology is often associated with different generations of wireless telecommunications systems for elements providing widely comparable functionality. However, example embodiments of the present disclosure may be equally implemented in different generations of wireless telecommunications systems, such as the 5G or new radio described below, and for simplicity certain terms may be used regardless of the underlying network architecture. That is, the use of a particular term in relation to certain example embodiments is not intended to indicate that the embodiments are limited to the particular generation of network with which the particular term is most associated.

New radio access technology (5G) wireless communication system

Fig. 2 is a schematic diagram illustrating a network architecture of a new RAT wireless communication network/system 200 based on previously proposed methods, which may also be adapted to provide functionality in accordance with embodiments of the present disclosure described herein. The new RAT network 200 presented in fig. 2 comprises a first communication cell 201 and a second communication cell 202. Each

communication cell

201, 202 comprises a control node (centralized unit) 221, 222 communicating with the core network element 210 over a respective wired or

wireless link

251, 252. The

respective control nodes

221, 222 also communicate with a plurality of distributed units (radio access nodes/remote Transmission and Reception Points (TRPs)) 211, 212 in their respective cells. Again, these communications may be over respective wired or wireless links. The

distribution units

211, 212 are responsible for providing radio access interfaces for communication devices connected to the network. Each

distributed unit

211, 212 has a coverage area (radio access footprint) 241, 242, wherein the sum of the coverage areas of the distributed units under control of the control node together define the coverage of the

respective communication cell

201, 202. Each

distributed unit

211, 212 includes transceiver circuitry for transmission and reception of wireless signals and processor circuitry configured to control the respective

distributed unit

211, 212.

In terms of broad top-level functionality, the core network component 210 of the new RAT communication network presented in fig. 2 may be broadly considered to correspond to the core network 102 presented in fig. 1, and the

respective control node

221, 222 and its associated distributed unit/

TRP

211, 212 may be broadly considered to provide functionality corresponding to the base station 101 of fig. 1. The term network infrastructure equipment/access node may be used to encompass these elements of a wireless communication system as well as more conventional base station type elements. Depending on the application at hand, the responsibility for scheduling transmissions scheduled on the radio interface between the respective distributed unit and the communication device may be in the control node/centralized unit and/or the distributed units/TRPs.

A first communication device or UE 260 is presented in fig. 2 as being within the coverage area of the first communication cell 201. Thus, the wireless communication device 260 may exchange signaling with the first control node 221 in the first communication cell via one of the distributed units 211 associated with the first communication cell 201. In some cases, communications for a given communication device are routed through only one of the distributed elements, but it is understood that in some other implementations (e.g., in soft handoff scenarios and other scenarios), communications associated with a given communication device may be routed through more than one distributed element.

Also represented in fig. 2 is a second communication device or UE 261 which is outside the coverage area of both the first communication cell 201 and the second communication cell 202 and therefore does not have direct access to the Radio Access Network (RAN) comprising the

control nodes

221, 222 and the

TRPs

211, 212. However, the second communication device 261 is within the coverage area of the signaling sent by the first communication device 260.

In the example of fig. 2, two

communication cells

201, 202 and two

communication devices

260, 261 are shown for simplicity, but it will of course be appreciated that in practice the system may comprise a large number of communication cells (each supported by a respective control node and a plurality of distributed units) serving a large number of communication devices.

It should also be understood that fig. 2 presents only one example of the proposed architecture of a new RAT communication system, in which methods according to the principles described herein may be employed, and that the functionality disclosed herein may also be applied in relation to wireless communication systems having different architectures.

Accordingly, the example embodiments of the present disclosure discussed herein may be implemented in a wireless telecommunications system/network according to various different architectures, such as the example architectures illustrated in fig. 1 and 2. Thus, it should be understood that the particular wireless communication architecture in any given implementation is not paramount to the principles described herein. In this regard, example embodiments of the present disclosure may be generally described in the context of communications between network infrastructure equipment/access nodes and communication devices, where the particular nature of the network infrastructure equipment/access nodes and communication devices will depend on the network infrastructure used for the current implementation. For example, in some cases, the network infrastructure equipment/access node may comprise a base station, such as LTE-type base station 101 shown in fig. 1, which is adapted to provide functionality in accordance with the principles described herein, and in other examples, the network infrastructure equipment/access node may comprise a control unit/

control node

221, 222 and/or

TRP

211, 212 of the type shown in fig. 2, which is adapted to provide functionality in accordance with the principles described herein.

It should also be understood that fig. 2 represents only one example of a proposed architecture for a new RAT-based telecommunications system in which methods according to the principles described herein may be employed, and that the functionality disclosed herein may also be applied to wireless communications systems having different architectures.

Thus, certain embodiments of the present disclosure as discussed herein may be implemented in a wireless telecommunications system/network according to various different architectures, such as the exemplary architectures shown in fig. 1 and 2. It should be understood that the particular wireless telecommunications architecture in any given implementation is not of primary significance to the principles described herein. Indeed, some embodiments of the present disclosure may be implemented by a wireless communication device without interacting with the features of the exemplary radio access networks shown in fig. 1 and 2, including but not limited to the base station 101, the

core networks

102, 210, the

control nodes

221, 222 and the TRP/DU 211. Thus, although in fig. 2 the first communication device 260 is shown as being within the coverage area of a cell of the wireless communication network and thus may communicate with the DU211, and the second communication device 261 is shown as being outside the coverage area, the present disclosure is not limited to such scenarios: some embodiments may be implemented when one, both, or neither of the first communication device 260 and the second communication device 261 are within the coverage area of the wireless communication network.

In embodiments of the present disclosure, the communication device 260 thus communicates with infrastructure equipment/access nodes, the specific nature of the network infrastructure equipment/access nodes and communication devices will depend on the network infrastructure used for the implementation at hand. For example, in some scenarios, the network infrastructure equipment/access node may comprise a base station, such as the LTE type base station 1 shown in fig. 1, which is adapted to provide functionality in accordance with the principles described herein, and in other examples the network infrastructure equipment may comprise a control unit/control node 40 and/or TRP 10 of the type shown in fig. 2, which is adapted to provide functionality in accordance with the principles described herein.

Fig. 3 provides a more detailed illustration of some of the components of the network shown in fig. 2. As a simplified representation, the DU211 comprises a transmitter 30, a receiver 32 and a controller or control processor 34 operable to control the transmitter 30 and the receiver 32 to transmit and receive radio signals to and from a first communication device 260 within the first cell 201 via a radio interface comprising uplink 67 and downlink 66 portions.

The first communication device 260 is shown as comprising a corresponding transmitter 49, receiver 48 and controller 44, the controller being configured to control the transmitter 49 and receiver 48 to transmit signals representing uplink data to the wireless communication network via the wireless access interfaces 66, 67.

In fig. 3, a second communication device 261 is shown, which may be substantially the same as or similar to the first communication device 260. As a simplified representation, the second communication device 261 comprises a transmitter 59, a receiver 58 and a controller or control processor 15 operable to control the transmitter 59 and the wireless receiver 58 to transmit and receive uplink and downlink radio signals with the first communication device 260 via the

sidelink connections

76, 77 using the wireless access interface provided by the first communication device 260. The signals exchanged between the first communication device 260 and the second communication device 261 may include side-link or device-to-device (D2D) communications. It should be understood that any of the first communication device 260 and the second communication device 261 shown in fig. 2 and 3 may be used to control their respective transmitters and receivers in such a manner as to transmit and receive sidelink communications directly with one or more other communication devices and thereby to communicate sidelink communications with these other communication devices. The specific protocol for establishing the

sidelink connections

76, 77 may be implemented according to different radio access technologies, such as WLAN, bluetooth, WiFi, 3G/UMTS, 4G/LTE and 5G/NR. Details of these protocols can be found in the relevant standards. Establishing a sidelink connection between two or more wireless communication devices may include utilizing a narrowband channel similar to that used in eMTC or NB-IoT.

In the case where one or both of the first communication device 260 and the second communication device 261 operate within the coverage area of a cell of the wireless communication network, such as the first cell 201, the communication resources for the

sidelink connections

76, 77 may be selected from a pool of resources allocated by the wireless communication network, such as by the DU211 or CU 221.

In the case where neither the first communication device 260 nor the second communication device 261 is operating within the coverage area of a cell of the wireless communication network, such as the first cell 201, the communication resources for the

sidelink connections

76, 77 may be selected from a pre-configured resource pool.

Thus, communication devices, such as the first communication device 260 and the second communication device 261 operating in a wireless telecommunications system, are provided with the functionality to communicate directly with each other without routing signaling through a RAN associated with one or more wireless communication networks in which the communication devices may be located within their coverage area. In some cases, using sidelink communications allows data to be more efficiently transferred from one communication device to another communication device because the data need not be separately transmitted to infrastructure equipment (such as DU 211) via the uplink of the wireless access interface and then retransmitted from the infrastructure equipment via the downlink. Sidelink communications may also be advantageously used to support relay communications. Referring to fig. 3, a second communication device 261 is shown outside the cell 201 served by the DU 211. A second communication device 261. Establishing the sidelink radio access interfaces 77, 76 between the first communication device 260 and the second communication device 261 may enable the second communication device 261 to communicate data with the DU211 (and thus the rest of the RAN/core network) by using the first communication device 260 as a relay node. For example, data to be sent from the second communication device 261 to the DU211 may be sent to the first communication device 260 via the uplink of the side link wireless access interface 77, and then the first communication device 260 sends (i.e. 'relays') the data to the DU211 via the uplink of the wireless access interface 67. Similarly, data to be sent from the DU211 to the second communication device 261 may be sent using downlink signaling via the downlink of the wireless access interface 66 to the first communication device 260 acting as a relay node, which in turn the first communication device 260 sends (i.e. 'relays') the data to the second communication device 261 via the downlink of the wireless access interface 76. In this way, the DU211 may serve the second communication device 261 via the first communication device 260 acting as a relay node. Such a relay node may be provided to enable the second communication device 261 to exchange data associated with any known service typically associated with the core network 210. Additionally or alternatively, the second communication device 261 may send or receive data associated with one or more application layer services provided via a further network (e.g., an external packet data network such as the internet) connected to the core network 210.

The

transmitters

30, 49, 59 and

receivers

32, 48, 58 shown in fig. 3 (as well as the other transmitters, receivers and transceivers described with respect to the examples and embodiments of the present disclosure) may also include radio frequency filters and amplifiers and signal processing components and devices to transmit and receive radio signals according to, for example, the 5G/NR standard. The

controllers

34, 44, 54 (and other controllers described with respect to examples and embodiments of the present disclosure) may be, for example, microprocessors, CPUs, or dedicated chipsets, etc., configured to execute instructions stored on a computer-readable medium, such as non-volatile memory. The process steps described herein may be performed by, for example, a microprocessor operating in conjunction with a random access memory according to instructions stored on a computer-readable medium.

As shown in fig. 3, the DU211 further comprises a network interface 50, the network interface 50 being connected to the CU 221 via the physical interface 16. Thus, the network interface 50 provides a communication link for data and signaling traffic from the DU211 to the core network 210 via the CU 221.

Use of sidelink communications

According to conventional operation, the first communication device 260 may initially transmit data to the second wireless communication device 261 in the first cell 201 with both the first communication device 260 and the second communication device 261 within the coverage area of the wireless communication network and, for example, served by infrastructure equipment associated with the first cell 201 and the second cell 202, respectively, of fig. 2. The data is sent to the associated control node 221 via one of the Distributed Units (DUs) 211 associated with the first communication cell 201. The data is then sent to the second communication device 261 via the

appropriate control node

221, 222 and/or the distribution unit 211. The particular path that the signalling takes within the interface (e.g. backhaul connection) of the radio access network between the control node/TRP receiving data from the first communication device 260 and the control node/TRP sending data to the second communication device 261 may be determined by the network according to any suitable protocol.

However, in some cases, the

communication devices

260, 261 are configured to transmit and receive signals representing data directly with

other communication devices

260, 261 without routing the signals through network infrastructure equipment/access nodes (e.g., radio access and/or core networks). Thus, in some cases, the first wireless communication device 260 may establish a wireless access interface to support communication with at least one additional wireless communication device (such as the second communication device 261). The communication may be referred to as device-to-device (D2D), vehicle-to-vehicle (V2V/V2X), or sidelink communication, which is at least partially characterized by not being routed through an entity forming part of a radio access network (e.g., a control node, a central unit, a distributed unit, a TRP, a transceiver station, a network entity, a nodeB, an enodeB, an eNB, a g-nodeB, a gNB, etc.) or part of a core network.

It should be appreciated that other network entities may support aspects of such sidelink communications. For example, one or more RAN/core entities may effectively reserve communication resources (e.g., within an uplink/downlink radio frame structure associated with one or more cells under RAN/core network control) that may be used for direct communication between the first communication device 260 and the second communication device 261. Thus, network-assisted coordination may avoid potential interference problems. For example, if a first communication device 260 within the coverage area of the first cell 201 attempts to exchange signaling with a second communication device 261, sidelink transmissions may interfere with uplink or downlink transmissions in the first cell 201 using a radio access interface provided by the DU211 according to one or more radio access interfaces provided by the RAN entity. Such interference may be reduced or avoided if the sidelink transmissions are restricted to reserved communication resources that would otherwise not be used for transmissions within the first cell 201.

Sidelink communications between communication devices may also be assisted by one or more RAN/core network entities by providing signaling that may assist in synchronization between two or

more communication devices

260, 261 prior to or during establishment of the sidelink connection. For example, two communication devices within the same cell may obtain synchronization with a network entity such as DU211 by receiving reference signaling on downlink radio resources, and may thus synchronize with each other accordingly. This may enable two communication devices that are seeking to establish a sidelink connection to forego certain aspects of the discovery and synchronization process that may otherwise be required to establish a wireless access interface to support device-to-device communication.

It should also be understood that sidelink communications may be established between two or more communication devices without direct assistance from a RAN/core of a wireless communication system, such as those shown in fig. 1 and 2. In these examples, the two wireless communication devices may establish a sidelink connection according to a discovery and connection procedure, which may be similar to a conventional RRC connection procedure used to establish a connection between the communication device 260 and a base station/TRP/control node or other cell serving entity common to conventional LTE or 5G environments. In some cases, sidelink communications may be established over unlicensed spectrum resources that are not controlled by the RAN. The use of these resources by the wireless communication device may be opportunistic based and may employ a Listen Before Talk (LBT) protocol to support coexistence with other entities seeking to transmit signals on the same resources. For example, it has been proposed in document R2-133840[2] to use the Carrier Sense Multiple Access (CSMA) method to provide a degree of coordination for sidelink transmissions of wireless communication devices by contention-based scheduling of each device. In practice, each wireless communication device first listens to identify which resources are currently being used and then schedules its own transmissions on the unused resources.

In many examples, a sidelink connection will be used to provide data exchange between two or more UEs moving relative to each other. This may be used in environments such as vehicle-to-vehicle (V2V), vehicle-to-everything (V2X), and more generally device-to-device (D2D) scenarios for sharing, for example, traffic information, safety-related information, and data from application layer services. Sidelink connections may also be used to provide relay services, enabling UEs or communication devices outside the network coverage area to access the network via an intermediate connection to a ('relay') UE within the coverage area of a cell of the wireless communication network, and thus have access to the wireless access interface provided by the radio access network of the wireless communication network.

In certain scenarios, such as V2V and V2X environments, UEs may move in and out of signaling range of each other very quickly. It is therefore expected that a sidelink connection between a first UE and a second UE may become unsuitable for supporting communication between UEs.

Embodiments of the present technology provide a method of operating a first wireless communications device to communicate with a second wireless communications device, the method comprising establishing a configuration for exchanging signalling with the second wireless communications device over a wireless interface, and receiving a handover command from the second wireless communications device over the wireless interface indicating that the first wireless communications device should modify an aspect of the current configuration for wireless communications. The method also includes providing a handover rejection indication to the second wireless communication device, wherein the handover rejection indication indicates to the second wireless communication device that the first wireless communication device is to continue operating according to its current configuration for wireless communication. The first wireless communication device continues to operate in the manner indicated by the handover command.

Embodiments of the present technology thus provide an improved handover procedure for sidelink communications in which a communication device that is the recipient of a handover command may determine not to adjust its communications in accordance with the handover command. Embodiments also provide preferences, capabilities and/or measurements associated with peer communication devices to be taken into account when selecting a new configuration for sidelink communication. In particular, radio resources that may be determined to be suitable by one of the peer communication devices may be determined to be unsuitable or less preferred than other radio resources by another of the peer communication devices.

Conventional network controlled handover

Fig. 4 illustrates aspects of a conventional handover procedure.

Initially, the communication device 104 (which may correspond to the communication device 260 of fig. 3) is served in the first cell 201 associated with the source infrastructure equipment 101a, which may be the first infrastructure equipment corresponding to the DU 211. The data 402 is sent from the communication device 104 to the core network 102 or from the core network 102 to the communication device 104 via the source infrastructure equipment 101 a.

The source infrastructure equipment 101a determines in process 404 that the communication device 104 should be served in a different cell in the future. The determination may be based on measurements of signals transmitted by the communication device 101 and received at the first infrastructure equipment 101a, and/or based on measurement reports transmitted by the communication device 101. The measurement report may include an indication of the results of measurements performed by the communication device 101 on signals transmitted by the first infrastructure equipment 101a and/or an indication of the results of measurements performed by the communication device 101 on signals transmitted by other infrastructure equipment, such as the second infrastructure equipment 101b (which may correspond to the DU 222 of fig. 3).

It should be appreciated that the determination that a handover should occur may be made according to various algorithms based on other factors. The scope of the present disclosure is not limited to any particular method of determining to perform a handover.

In response to the determination 404, the source infrastructure equipment 101a selects a candidate cell. The selection may be based on a measurement report sent by the communication device 104. In the example of fig. 4, the source infrastructure equipment 101a selects a second cell associated with the second infrastructure equipment 101 b.

Thus, the source infrastructure equipment 101a may initiate a handover procedure with the target infrastructure equipment 101 b. In the example of fig. 4, source infrastructure equipment 101a and target infrastructure equipment 101b are directly connected (such as through an X2 or Xn inter-infrastructure equipment connection), however in some examples, the handover procedure may include signaling sent via but not involving core network 102 (which may correspond to core network 210 of fig. 3). Handover preparation may be performed without specific interaction with the core network 102.

As part of handover preparation, the source infrastructure equipment 101a sends a handover request 406 to the target infrastructure equipment 101b to allocate communication resources for the communication device 104 in the new cell. In response, the target infrastructure equipment 101b sends a handover request acknowledge message 410 to the source infrastructure equipment 101a, containing parameters for using the communication device 104 in the new cell. The parameters may include communication resources, identification, and configuration parameters to be used by the communication device 104 in the target cell. The parameters are forwarded to the communication device 104 in the RRC reconfiguration message 412.

In response to receiving the RRC reconfiguration message 412, the communication device 104 accesses the new cell, e.g., using a random access procedure 414.

In the example of fig. 4, at this stage, an entity in the core network 102 is unaware that the serving cell of the communication device 104 has changed, and data 416 received from the core network 102 for onward transmission by the source infrastructure to the communication device 104 is forwarded to the target infrastructure equipment 101 b.

To inform the core network 102 of the change in serving cell (and, more particularly, serving infrastructure equipment), the target infrastructure equipment 101b may send a path switch request message 418 to the core network 102, in response to which the core network 102 then sends data 420 for the communication device 104 to the target infrastructure equipment 101b instead of the source infrastructure equipment 101 a.

As can be appreciated from the foregoing description, in conventional wireless telecommunications networks, handover decisions are made only by entities (e.g., control nodes, base stations, infrastructure equipment) within the RAN/core network, and not by the communication devices themselves. As discussed with respect to the process of fig. 4, the source infrastructure equipment 101a associated with the currently active cell (i.e., the first cell 201) has determined that the communication device 104 should be handed over to the second cell 202, informing the communication device 104 that it is being handed over to the second cell 202.

Thus, the participation of the communication device 104 in this process is limited to sending/receiving signaling associated with making measurements that support decisions made by entities within the RAN/core network (e.g., source infrastructure equipment 101a) regarding the target cell best suited for handover. The source infrastructure equipment 101a has configured the target infrastructure equipment 101b to handover to the second cell 202, notifies the communication device 104 of the handover, provides any necessary configuration information for the communication device 104 to access the second cell 202, and then instructs the communication device 104 to perform the handover.

This conventional handover scenario may be considered a master/slave arrangement because one or more entities in the RAN/core network make a unilateral decision on handover of the communication device, and the communication device simply responds to the handover indication in an indicative manner. According to these conventional scenarios, a communication device that has been provided with a handover indication continues to modify its wireless communication (e.g., by reconfiguring radio resources for ongoing communications and/or connecting to a different network entity).

This form of master/slave approach may be considered suitable in the context of communication device handover between cells/radio resources under control of a host network, for example in the conventional LTE/NR scenario schematically represented in fig. 1 and 2. One advantage of this approach is that in most cases the host network will have a wider understanding of the radio conditions and mobility scenarios within its geographic coverage area than any individual communication device and may be considered more suitable for making decisions on handover configurations than any individual communication device.

However, the inventors of the present technology disclosed herein have identified a problem that may arise if this form of conventional handover procedure is applied to handover in an environment in which communication devices communicate directly with each other via sidelink communications.

In a peer to peer communications scenario described further herein, whereby the first communications device communicates with the second communications device via a sidelink (e.g. in the D2D, V2V, V2X scenario), the first communications device may determine that an upcoming communication with the second communications device is suitable for using a different radio resource and/or that a communication with the second communications device is suitable via a further communications device.

An embodiment of the present technology provides a method of operating a first wireless communications device to communicate with a second wireless communications device, the method comprising: transmitting or receiving a signal representing data to or from a second wireless communication device over a wireless interface, the signal being transmitted or received by the second wireless communication device according to the current configuration; determining that the current configuration is to be changed to a new configuration; sending a handover command to the second wireless communication device over the wireless interface, the handover command including an indication that the new configuration replaces the current configuration; and receiving a handover rejection indication from the second wireless communication device via the wireless interface, the handover rejection indication indicating to the first wireless communication device that the second wireless communication device is to continue operating according to the current configuration.

Embodiments of the present technology provide a handover procedure for modifying a configuration of a communication device for transmitting signals via a sidelink connection with another communication device.

Fig. 5 is a schematic diagram illustrating a peer-to-peer handover scenario to which methods according to embodiments of the present disclosure may be applied. Fig. 5 shows four

communication devices

511, 512, 513, 514 that may be configured to operate in the manner set forth herein with respect to the communication device 104 shown in fig. 1 and the

communication devices

260, 261 shown in fig. 2 and 3. Thus, the

communication devices

511, 512, 513, 514 are able to establish a side link connection as long as they are within range and the radio conditions at the time are suitable. In other words, the first communication device is configured to discover and establish a sidelink RRC connection with the second communication device via the sidelink wireless access interface in the manner described herein with respect to the first communication device 260 and the second communication device 261 shown in fig. 3. The

communication devices

511, 512, 513, 514 may comprise mobile communication devices, for example, the communication device 512 and the communication device 513 may be implemented within a mobile phone and/or a vehicle and/or a personal computing device such as a laptop or tablet computer. In some embodiments, one or more of the

communication devices

511, 512, 513, 514 comprise a vehicle.

Also shown in fig. 5 are first through

third cells

501, 502, 503, which may be implemented in accordance with the techniques described herein for providing a wireless access interface. For example, any of the first to

third cells

501, 502, 503 may comprise a cell 101 served by a base station as shown in fig. 1, or a

cell

201, 202 served by a

control node

222, 221 and/or a

TRP

211, 212 as shown in fig. 2. In some embodiments, the first to

third cells

501, 502, 503 may be configured according to UTRAN, WLAN, bluetooth, WiFi, 3G, LTE, and 5G. In other embodiments, the first to

third cells

501, 502, 503 may not be present and the

communication devices

511, 512, 513, 514 may be considered outside the coverage area of any other wireless network infrastructure.

In fig. 5, the first communication device 511 and the second communication device 512 have established a configuration for exchanging signaling through the sidelink wireless access interface 520, thereby achieving direct signaling exchange. It should be understood that in some cases, the first communication device 511 may be transmitting data without receiving data from the second communication device 512. The sidelink connection 520 may have been established according to any conventional method suitable for device discovery and RRC connection used between communication devices, such as described in [3 ]. The specific implementation of this procedure will depend on the technology used to support the radio access interface between UEs in the specific implementation. In some cases, the procedure for establishing an initial sidelink connection between the first communication device 512 and the first communication device 511 may be the same or similar to the RRC connection signaling procedure used by the UE to connect to the cell in a conventional LTE/5G/NR scenario.

In some examples, beacon signaling transmitted by one or both of the first communication device 511 and the second communication device 512 may be used to support device discovery, and synchronization signaling, such as device-to-device synchronization signals (D2DSS), may be transmitted by the first communication device 511 and the second communication device 512 to support synchronization. The signaling exchanged over the sidelink connection between the first communication device 511 and the second communication device 512 is sent on radio resources that may be associated with a particular frequency range. The frequency range may be within a frequency band used by the RAN of the network (e.g., a frequency band used to support communications on any of the

cells

501, 502, 503), or within an unlicensed frequency band.

According to a first exemplary scenario, the first communication device 511 and the second communication device 512 are moving in the directions indicated by the respective arrows a1 and a2 in fig. 5. At some stage, the first communication device 511 determines that an aspect of the current configuration used by the second communication device 512 for wireless communication should be modified. In some embodiments, this includes determining that the radio resources currently used to support sidelink communications should be changed. This may be because, for example, radio conditions on the wireless access interface supporting sidelink 520 may deteriorate due to mobility and/or fluctuating radio conditions associated with environmental factors or the effects of simultaneous transmissions by other devices in the radio environment. In the example of fig. 5, when the first and

second communication devices

511 and 512 travel in the directions indicated by respective arrows a1 and a2, the transmission associated with the second cell 502 may cause degraded interference on the sidelink between the first and

second communication devices

511 and 512.

Thus, in the present scenario, the first communication device 511 determines (e.g. using methods such as those described in the procedure shown in fig. 4 in relation to the first cell 201) that upcoming signaling exchanged with the second communication device 512 should be transferred to a different radio resource. Thus, the first communication device 511 identifies a target set of radio resources that it deems suitable to support the upcoming signaling between the first communication device 511 and the second communication device 512, e.g. using conventional measurement methods. These target resources may include resources within a frequency band used for communication by one or more of the first to

third cells

501, 502, and 503, or may include resources within an unlicensed frequency band.

According to an embodiment of the present disclosure, the first communication device 511 sends a handover command to the second communication device 512 over the sidelink wireless interface 520 indicating that the second communication device 512 should modify an aspect of the current configuration for wireless communication. In the present scenario, the handover command sent to the second communication device 512 comprises an indication of a target set of radio resources to be used by the second communication device 512 for exchanging upcoming signaling with at least one other communication device. As further set forth herein, the further communication device may be a further device, such as the third communication device 513 or the fourth communication device 514 schematically shown in fig. 5. However, in many cases, the other communication device may be the first communication device 511 that transmits the handover command.

In some embodiments, signaling including a handover command is sent over sidelink 520. In some embodiments, the handover command may be routed through other network entities (e.g., a RAN of the type schematically illustrated in fig. 1 and 2). This signaling may be referred to as a handover command and may be considered an indication that the first communication device 511 intends to handover upcoming signaling between the first communication device 511 and the second communication device 512 to a different time and/or frequency resource. The handover command may be implemented in the same or similar form as the RRC connection reconfiguration message (e.g., corresponding to the handover indication 412 sent in the first cell 201 in the procedure shown in fig. 4). In some cases, the second communication device 512, upon receiving the handover command, may reconfigure its communication with the first communication device 511 such that it transmits/receives the upcoming signaling on the target radio resource indicated by the handover command.

However, in accordance with embodiments of the present technique, in some cases, the second communication device 512 may determine not to modify its communication with the first communication device 511 in the manner indicated by the handover command. For example, in one exemplary scenario illustrated in fig. 5, the second communication device 512 may be subject to interference on the target radio resource indicated by the handover command due to its proximity to the third cell 503.

This is in contrast to conventional handover scenarios such as that shown in fig. 4, where a communication device receiving a handover command needs to comply with the handover command and modify its configuration accordingly.

Accordingly, the techniques disclosed herein may provide an improved handover procedure for sidelink communications, as, for example, changing the configuration of upcoming signaling to use a target radio resource that may be subject to interference may be avoided.

According to a second scenario shown in fig. 5, the first communication device 511 and the second communication device 512 have an established sidelink 520 as described before and are moving in the direction indicated by the respective arrows B1 and B2. In this case, the first communication device 511 having the current sidelink connection 520 to the second communication device 512 determines that the second communication device 512 should exchange upcoming signaling with a further network entity. For example, the first communication device 511 may send data from the application layer service to the second communication device 512 and determine that another communication device or cell service entity (such as infrastructure equipment associated with one of the first through third cells 501-503) may be better suited to serve future data transmissions to the second communication device 512. This may be due to mobility (e.g. because the first communication device 511 and the second communication device 512 move out of range of each other due to their movement in the respective directions B1 and B2) or application layer changes (e.g. the first communication device 511 is no longer able to provide access to the application layer services required by the second communication device 512) or because the first communication device 511 wants to retune its transceiver to a different frequency band.

In some cases, the first communication device 511 may have served as a relay node to provide a communication channel between the second communication device 512 and the infrastructure associated with the second cell 502 according to a method such as set forth herein with reference to fig. 3. In this case, the first communication device 511 may itself be moving out of the coverage area of the second cell 502 and thereby determine that it will no longer be able to provide relay service to the second communication device 512. However, these scenarios are exemplary, and it will be appreciated that there are many potential reasons why the first communication device 511 may determine that the second communication device 512 should modify aspects of the current configuration for wireless communication to exchange data with another wireless communication device.

In some cases, the second communication device 512 may have served as a relay node to provide a communication channel between the first communication device 511 and the infrastructure associated with the second cell 502. The second communication device 512 may additionally act as a relay node with respect to one or more additional communication devices.

According to some embodiments of the present disclosure, the determination by the first communication device 511 that an aspect of the current configuration used by the second communication device 512 for wireless communication should be modified does not require modification of the sidelink 520 between the first communication device 511 and the second communication device 512, but rather includes determining that the first communication device 511 should seek to establish a new connection or modify an existing connection to another communication device/cell.

Thus, according to embodiments of the present disclosure, the first communication device 511 identifies one or more target communication devices with which the second communication device 512 is to exchange upcoming signaling, e.g., using conventional discovery and/or measurement methods. For example, the first communication device 511 may use an appropriate technique to determine a target communication device with which the second communication device 512 is to exchange upcoming signaling. The procedure for determining the capabilities of the neighboring cells/communication devices and thus their suitability for exchanging signaling with the second communication device 512 may be according to the methods described elsewhere herein or conventional methods known in the art of D2D, V2V communications.

According to an embodiment of the present disclosure, the first communication device 511 sends a handover command to the second communication device 512 over the wireless interface 520 indicating that the second communication device 512 should modify aspects of the current configuration for wireless communication. The command may broadly correspond to the handover indication 412 described with respect to fig. 4. In the present exemplary scenario, the handover command sent to the second communication device 512 includes an indication of the target communication device with which the second communication device 512 is to exchange upcoming signaling (e.g., establish a sidelink connection). As further set forth herein, the target communication device may be the third communication device 513 or the fourth communication device 514 as schematically shown in fig. 5, or infrastructure equipment forming a cell being part of the RAN, such as the first to

third cells

501, 502, 503 as schematically shown in fig. 5.

In an exemplary scenario, the first communication device 511 may indicate that the third communication device 513 is the target communication device, in accordance with embodiments of the present technology. That is, the handover command indicates that the second communication device 512 is to modify its configuration to communicate directly with the third communication device 513. The communication between the first communication device 511 and the second communication device 512 may then accordingly take place by means of data relayed by the third communication device 513.

However, according to this exemplary scenario, the second communication device 512 is moving in direction B2 and thus moving away from the target third communication device 513. Thus, the second communication device 512 determines that the target third communication device 513 is an unsuitable candidate with which to exchange the upcoming signaling. For example, the second communication device 512 may be out of range of the target third communication device 513, or the second communication device 512 may determine that it and the target third communication device 513 may not be able to exchange signaling due to their associated circuit/radio access configurations being incompatible.

It should be appreciated that there may be many reasons why the second communication device 512 does not want to or cannot exchange upcoming signaling with the target third communication device 513. However, according to a conventional handover scenario such as that shown in fig. 4, and in which the first communication device 511 effectively plays the role of serving infrastructure equipment corresponding to the current serving cell, the second communication device 512 will be required to comply with the handover command. In this example, the result of such adherence may be that the second communication device 512 and the third communication device 513 fail to establish a sidelink, or establish a suboptimal sidelink in terms of radio quality or some other relevant parameter.

Fig. 5 thus presents two exemplary scenarios in which a conventional handoff method according to one or more principles employed in a handoff of the type set forth in fig. 4 may be inadequate or result in a sub-optimal selection of radio resources and/or target communication devices for use by a given communication device for sidelink communications in a peer-to-peer communication environment, such as a D2D, V2V, or V2X scenario.

Fig. 6 is a ladder diagram schematically representing aspects of a method according to some embodiments of the present disclosure. In particular, the figure represents operations and signaling exchanges associated with a first communication device 611 and a second communication device 612 (which may be considered to correspond to the first communication device 511 and the second communication device 512 schematically illustrated in fig. 5). Also shown is infrastructure equipment 602 that provides a wireless access interface in a cell that may be established according to LTE/NR techniques described further herein. In accordance with some embodiments of the present disclosure, the infrastructure equipment 602 may be configured to exchange signaling with one or both of the first wireless communication device 611 and the second wireless communication device 612.

The process represented in fig. 6 begins at step T1, where it is assumed that the first wireless communication device 611 has established a configuration for exchanging signaling with the second communication device 612 over the sidelink wireless interface. Thus, the first wireless communication device 611 and the second wireless communication device 612 are configured to exchange data directly with each other through a sidelink connection. The sidelink may be configured and established in accordance with any of the principles set forth further herein or known in the relevant art for establishing a wireless interface between two communication devices.

In step T2, the first communication device 611 determines that an aspect of the current configuration used by the second communication device 612 for wireless communication should be modified. The determination may be based on one or more factors related to mobility, radio channel quality, provision of relay services, provision of application layer services, and/or the like.

In particular, in some embodiments, the determination may be based on measurements of the first communication device 611 of a sidelink radio link between the first communication device 611 and the second communication device 612. The measurements may be packet loss rate, received signal strength, received signal quality and/or bit error rate. The determining may include determining that a side link radio link based handover criterion is satisfied.

In some embodiments, at step T1, the first communication device 611 provides data from the application layer service to the second communication device 612. The determination at step T2 may include a determination that the first communication device 611 is no longer able to provide such data (e.g., because the device acquired data from another device from which it no longer has connectivity via another sidelink or via infrastructure equipment associated with the wireless communication network).

In some embodiments, the determination may be based on one or more measurement report indications sent by the second communication device 612 to the first communication device 611. The measurement report indication may comprise an indication of a measurement result performed by the second communication device 612 of the sidelink radio link between the first communication device 611 and the second communication device 612. The measurements may be packet loss rate, received signal strength, received signal quality and/or bit error rate. The determination may include determining that a side link radio link based handover criterion is satisfied, as measured by the second communication device 612.

In some embodiments, the determination may be based on a predetermined preference to operate using one or more particular frequency bands. For example, the first communication device 611 may be configured according to a predetermined preference to use a specific unlicensed frequency band for a preferred operation, instead of the frequency band used for the sidelink connection in step T1.

It should be appreciated that the determination of the handover at step T2 may be based on a combination of criteria and may include criteria in addition to or instead of those specifically described herein.

In step T3, the first communication device 611 determines a target set of radio resources to be used by the second communication device 612 for exchanging upcoming signaling with at least one other communication device. The at least one other communication device may be the first communication device 611, infrastructure equipment of a radio access network, such as the infrastructure equipment 602, or another mobile communication device (not shown). In the example of fig. 6, infrastructure equipment 602 forms a wireless access interface that provides service within a cell. The first communication device 611 is located within a cell and may therefore communicate with the infrastructure equipment 602.

As further set forth herein, these resources may be determined by any suitable method. For example, the first communication device 611 may make measurements of channel conditions on candidate resources within one or more frequency bands and determine that a certain set of radio resources appears suitable for supporting upcoming signaling between the second communication device 612 and at least one other communication device. As shown in optional step T4, the first communication device 611 may exchange signaling with another entity, such as the second communication device 612 or the infrastructure equipment 602, to receive information that may be used by the first communication device 611 to determine the set of target radio resources.

In an optional step T5, the first communication device 611 may exchange signaling with the infrastructure equipment 602 requesting reservation of radio resources in the cell corresponding to the target set of radio resources. This signaling may be referred to as a resource reservation request. In accordance with some embodiments, the reservation of radio resources by the infrastructure equipment 602 comprises avoiding scheduling future transmissions on a set of radio resources (e.g., within a radio subframe structure used to provide the wireless access interface) that overlap with the target radio resources such that an upcoming signaling exchange between the second communication device 612 and the at least one other communication device using the target radio resources is not interfered with from the scheduled transmissions within the cell controlled by the infrastructure equipment 602.

In some embodiments, as part of the signaling exchange for reserving radio resources within a cell, a timer may be established to control when reserved resources may be released (i.e., may be used without restriction) in the cell. Thus, if the reserved resources are not used for any signaling exchange involving the second communication device 612 before the timer expires, the infrastructure equipment 602 will release the reserved resources. The release may include enabling resources to be scheduled for transmission associated with operation of the cell. Although step T5 has been explained with reference to the infrastructure equipment 602 and the corresponding cell, it should be understood that the first communication device 611 may request other entities (e.g. other communication devices) to reserve radio resources in order to support the upcoming signaling between the second communication device 612 and the at least one other communication device on the target radio resources indicated by the handover command.

In step T6, the first communication device 611 sends a handover command to the second communication device 612 indicating that the second communication device 612 should modify aspects of the current configuration of wireless communication. The handover command may comprise an RRC reconfiguration message indicating a target set of radio resources determined by the first communication device 611 in step T3 and potentially reserved by a further network entity such as the infrastructure equipment 602 in optional step T5. The signaling comprising the handover command may be transmitted over a sidelink between the first communication device 611 and the second communication device 612 or may be routed through other network entities, for example, through signaling exchanges between each of the first communication device 611 and the second communication device 612 and the infrastructure equipment 602.

In step T7, the second communication device 612, in response to receiving the handover command, determines that operation will continue using the current configuration and/or that the current configuration for wireless communication will not be modified in accordance with the handover command.

For example, the second communication device 612 may determine that the target set of radio resources indicated by the handover command is not suitable for use, e.g., due to interference to the resources as determined via measurements made by the second communication device 612. The target set of resources may additionally or alternatively be determined to be inappropriate because they are within a frequency band in which the second communication device 612 is unable to transmit or receive. For example, the target set of resources may be within an unlicensed frequency band that the second communication device 612 is not configured for transmission or reception of signals.

In the case where the second communication device 612 acts as a relay node to provide a communication channel between the first communication device 611 and the infrastructure associated with the cell and in some examples also acts as a relay node for one or more further communication devices, the second communication device 612 may determine that the target set of radio resources indicated by the handover command is not suitable for use based on requirements associated with providing relay functionality with respect to the first communication device 611 and/or the one or more further communication devices. For example, the second communication device 612 may determine that the target set of radio resources indicated by the handover command are not suitable for use because they are not sufficient to allow continued functionality as a relay device.

Additionally or alternatively, the second communication device 612 may determine that the target set of resources is subject to 'listen before talk' transmission requirements (such as according to a carrier sense multiple access, CSMA, protocol), possibly preventing communication between the first communication device 611 and the second communication device 612. For example, the second communication device 612 may have detected frequent transmissions using some or all of the target set of resources, which would prevent one or both of the first communication device 611 and the second communication device 612 from transmitting using the target set of resources according to a listen-before-talk protocol, and/or would significantly reduce the available data rate that can be achieved using the target resources for sidelink connections.

In some embodiments, additionally or alternatively, the second communication device 612 may determine a more appropriate or preferred set of radio resources for exchanging upcoming signaling. In some embodiments, in response to receiving the handover command in step T6, the second communication device 612 may determine a preferred target set of radio resources that is determined to be more suitable candidates for exchanging upcoming signaling with the at least one other communication device than the target set of radio resources indicated by the handover command received from the first communication device 611. The process for determining the preferred target set of radio resources is not critical and may follow any of the methods set forth further herein (e.g., as described above with respect to the first communication device 611 in steps T3 and T4) or other known methods for determining suitable radio resources known in the art.

Thus, determining at step T7 that the second communication device 612 will not modify its current configuration for wireless communication in accordance with the handover command may be responsive to the identification of an alternative, more preferred radio resource.

In some embodiments, determining not to change to the new configuration is in response to one or more of:

determining that the proposed radio resources are not suitable (e.g., due to interference, listen-before-talk requirements, application level preferences, pre-configuration preferences, and/or corresponding device capabilities),

-identifying alternative, more preferred radio resources, and

-identifying an alternative communication device for establishing the sidelink connection.

In step T8, in response to determining that the second communication device 612 will not modify the current configuration for wireless communication in accordance with the handover command, the second communication device 612 sends a handover rejection indication to the first communication device. The handover rejection indication indicates to the first communication device 611 that the second communication device 612 does not intend to modify the current configuration for wireless communication in the manner indicated by the handover command and will continue to operate using the current configuration.

It should be appreciated that this aspect of the peer handover procedure shown in figure 6 differs from the conventional handover scenario shown in figure 4 in that, via the handover rejection indication, a mechanism is provided for the communication device that has received the handover command to indicate that it will not comply with the handover command by exchanging upcoming signaling using the target radio resources indicated in the handover command. In other words, the handover reject indication provides a mechanism for the second communication device 612 to reject the handover request. Notably, this is different from conventional handover failure indications that may be sent by a communication device that has attempted to establish a new connection using the indicated target resource but failed in accordance with embodiments of the present disclosure in that no attempt is made to establish any connection using the indicated target resource.

It should be appreciated that the handover rejection indication may be implemented in a variety of ways. For example, in some embodiments, the handover rejection indication comprises signaling sent to the first communication device 611 over a sidelink connection between the first communication device 611 and the second communication device 612. In some embodiments, the handover rejection indication comprises signaling sent to the first communication device 611 via one or more intervening entities, e.g., by using communication resources associated with the cell controlled by the infrastructure equipment 602 and associated entities forming part of the RAN/core network. In other words, if the first communication device 611 and the second communication device 612 have respective connections to a conventional (i.e., non-peer/D2D/V2V/V2X) network infrastructure, the handover rejection indication may be routed between the first communication device 611 and the second communication device 612 via the network infrastructure according to conventional communication protocols in the network (e.g., as user plane data).

In other embodiments, the handover rejection indication is implicitly indicated to the first communication device 611. For example, when the first communication device 611 sends a handover command to the second communication device 612, the first communication device 611 may start a timer. If the second communication device 612 fails to meet a certain condition before the timer expires, the first communication device 611 may interpret this as including an implicit handover rejection indication for the second communication device 612.

The condition to be satisfied may include sending, by the second communication device 612 to the first communication device 611, signaling indicating that the second communication device 612 intends to exchange upcoming signaling on the target resource, or otherwise determining that the second communication device 612 is exchanging signaling on the target resource. The timer duration and conditions may be defined by a standard, established according to a setup procedure originally used to establish the sidelink, or otherwise established via signaling between the first communication device 611 and the second communication device 612. In some embodiments, the handover reject indication comprises a reject cause indication indicating a reason why the handover command/target radio resource has been rejected by the second communication device 612. Based on the rejection cause indication, the first communication device 611 may determine an alternative target radio resource and may send a subsequent handover command to the second communication device 612 indicating the alternative target radio resource.

In some embodiments, in association with providing the handover rejection indication to the first communication device 611, the second communication device 612 may send or otherwise indicate to the first communication device 611 the preferred target set of radio resources determined by the second communication device 612 as part of step T6 described above. This may be included in the handover rejection indication. In some embodiments, the handover rejection indication comprises an RRC reconfiguration message sent to the first communication device 611 over a suitable communication link, the RRC reconfiguration message comprising an indication of a preferred target set of radio resources. The indication of the preferred target set of radio resources may be sent to the first communication device 611 at a different time than the handover rejection indication.

Thus, in addition to a mechanism that enables the second communication device 612 to indicate to the first communication device 611 that it will not modify the current configuration for wireless communication in the manner indicated by the handover command, embodiments of the present technology also provide for the second communication device 612 to notify the first communication device 611 of the preferred modification to its current configuration. As further set forth herein with respect to fig. 5, this may be useful because the first communication device 511 may not know local radio conditions (such as local interference scenarios or loading of radio resources) in the vicinity of the second communication device 512 and thus the first communication device 511 may not have sufficient knowledge of the environment of the second communication device 512 to be able to select the most appropriate radio resources for the second communication device 512 to exchange the upcoming signaling.

In step T9, the first communication device 611 determines that the procedure of modifying the current configuration should not be initiated according to the handover command in response to receiving the handover reject indication from the second communication device 612. This is in contrast to a handover procedure according to conventional principles, according to which, after sending a handover command, the infrastructure equipment may assume that the communication device will at least attempt to implement the configuration change indicated by the handover command.

Thus, having sent a target set handover command to the second communication device 612 indicating radio resources to be used by the second communication device 612 for exchanging upcoming signaling with at least one other communication device, the first communication device 611 may determine that it does not itself send signaling on the target radio resources to the second communication device 612, or indicate to another communication device/cell that it may exchange signaling on the target radio resources with the second communication device 612, in response to receiving the handover rejection indication.

In some embodiments, in optional step T10, the first communication device 611 indicates to the infrastructure equipment 602, which has reserved radio resources as part of optional step T5, that the reserved resources may be released. For example, as part of step T5, the infrastructure equipment 602 may reserve certain frequency/time resources on the radio subframe structure associated with the radio access interface provided by the infrastructure equipment 602 forming the cell, so as not to cause interference to upcoming signaling to be exchanged between the second communication device 612 and another entity on the target radio resource indicated by the handover command. However, once the first communication device 611 receives the handover rejection indication from the second communication device 612, the first communication device 611 may send a release indication to the infrastructure equipment 602 indicating that the target radio resources are no longer needed.

The release indication may comprise explicit signaling sent by the first communication device 611 to the infrastructure equipment 602 or may be implicitly indicated to the infrastructure equipment 602 by the expiration of a timer associated with the resource reservation received in step T5.

In response to receiving the release indication, the infrastructure equipment 602 may release the resources reserved in step T5 and allocate them to subsequent data transmissions within the cell.

In some embodiments, after the optional step T10, the process continues to step T2 whereby the first communication device 611 determines that an aspect of the current configuration used by the second communication device 612 for wireless communication should be modified. The first communication device 611 may thus determine not to seek to modify the current configuration, and thus the first communication device 611 and the second communication device 612 may continue to exchange signaling in accordance with the current configuration used by the second communication device 612 for wireless communication on the sidelink between the first communication device 611 and the second communication device 612.

In some embodiments, the first communication device 611 may instead proceed to step T3 and determine a target set of radio resources to be used by the first communication device 611 for exchanging upcoming signaling with at least one other communication device. The determination may be mainly as described previously, however, if the handover rejection indication sent by the second communication device 612 comprises an indication of why the handover command/target radio resource has been rejected by the second communication device 612, the first communication device 611 may take this information into account in step T3. In one case, the second communication device 612 may have indicated that the handover command was denied because the target resource is in a frequency band that the second communication device 612 cannot access. Thus, during step T3, the first communication device 611 may ensure that the new target set of radio resources does not include resources within the frequency band.

In other cases, however, according to step T11, the first communication device 611 indicates to the second communication device 612 that the second communication device 612 can optionally exchange signaling with at least one other communication device using the preferred target set of radio resources sent to the first communication device 611 in association with the handover rejection indication in step T7. The indication may include explicit signaling, for example, sent over a sidelink between the first communication device 611 and the second communication device 622, or routed via the network infrastructure of a conventional network. In some embodiments, the signaling comprises RRC configuration signaling as set forth elsewhere herein. In other embodiments, the first communication device 611 may implicitly indicate to the second communication device 612 that the second communication device 612 may exchange signaling with at least one other communication device using the preferred target set of radio resources, e.g., by not sending a further handover command message (or other signaling) to the second communication device 612. It should be appreciated that the first communication device 611 may indicate to the second communication device 612 that it may exchange signaling with at least one other communication device using the preferred target set of radio resources in a number of ways. In some cases, the preferred target set of radio resources sent from the second communication device 612 to the first communication device 611 includes a list of preferred sets of target radio resources, and the first communication device 611 may determine the preferred set of target radio resources from the list. To support this determination, the first communications device 611 may make measurements of radio conditions on a plurality of sets of radio resources included in the list, thereby determining that a given set is a preferred candidate. This may be because the first communication device 611 intends to exchange signaling with the second communication device 612 using one of the sets of radio resources comprised in the list and thus determines that the preferred candidate set of radio resources is best suited to support the signaling, e.g. in view of current radio conditions in the vicinity of the first communication device 611. After making this determination, the first communication device 611 may then indicate to the second communication device 612 that the second communication device 612 may use those sets of radio resources on the preferred target radio resource list to exchange signaling with at least one other communication device.

As part of stage T11, the first communication device 611 may send signaling to the cell 602 and/or other entity to reserve resources corresponding to the preferred set of target radio resources in accordance with the method of step T5.

In optional step T12, either of the first communication device 611 and the second communication device 612 may indicate to their cell (e.g., cell 602) within the coverage area the aspects of the configuration to be used for exchanging signaling between the second communication device 612 and the target wireless communication device. This signaling may be implemented in much the same way as the resource reservation request of step T5, as it indicates to the cell 602 the set of resources to be used for establishing the connection between the second communication device 612 and the target wireless communication device, so that the cell 602 can avoid interfering with the signaling exchange between the second communication device 612 and the target wireless communication device. This step may also include informing the cell 602 of the handover so that the cell 602 and/or a core network entity connected to the cell 602 may use this information in its own tracking, mobility, scheduling and measurement procedures.

In step T13, the second communication device 612 exchanges data with at least one other wireless communication device using the preferred target set of radio resources. In some example embodiments, the at least one other wireless communication device is the first communication device 611, so the procedure outlined in relation to steps T1 to T12 may be considered to include means to transfer sidelink communications between the first communication device 611 and the second communication device 612 from one set of radio resources to another. In some such embodiments, this may include an inter-frequency handover to reconfigure the sidelink so that it may continue to be used to support signaling exchanges between the first communication device 611 and the second communication device 612, albeit on a different frequency. Thus, as described further herein, in some cases, the first communication device 611 may use the handover procedure to establish a sidelink connection over a resource within the unlicensed frequency band, e.g., to respond to an overload of a current resource being used to support a sidelink within a frequency band associated with a cell within a coverage area in which one or both of the first communication device 611 and the second communication device 612 are located.

In the example of fig. 6, another communication device with which the second communication device 612 directly communicates via a sidelink connection after the handover procedure is the first communication device 611.

In some embodiments, as shown in fig. 7 and described below, the sidelink connection includes a relay communication device such that another communication device with which the second communication device 612 directly communicates after the handover procedure is the relay communication device. Thus, the target radio resource indicated in the handover command may be used for transmitting signaling between the second communication device 612 and the relay communication device.

FIG. 7 is a ladder diagram schematically representing aspects of a method according to an embodiment of the disclosure. In particular, the figure represents the procedures and signaling exchanges associated with the first to fourth

wireless communication devices

711, 712, 713, 714 (which may be considered to correspond to the first to fourth

wireless communication devices

511, 512, 513, 514 schematically illustrated in fig. 5; the first communication device 711 and the second communication device 712 may substantially correspond to the first communication device 611 and the second communication device 612 illustrated in fig. 6). Also shown is infrastructure equipment 701 providing a cell, which may be established according to LTE/NR techniques described further herein and which may be configured to exchange signaling with one or more of the first through

fourth communication devices

711, 712, 713, 714, according to some embodiments of the present disclosure.

The process represented in fig. 7 starts in step R1, where the first communication device 711 has established a configuration for exchanging signaling with the second communication device 712 over the wireless interface. The first communication device 711 and the second communication device 712 are thus configured to exchange data directly with each other through a sidelink connection, as described above with respect to step T1 of fig. 6.

In step R2, the first communication device 711 determines that an aspect of the current configuration used by the second communication device 712 for wireless communication should be modified. Thus, step R2 may substantially correspond to step T2 described above with respect to the process of fig. 6.

In step R3, the first communication device 711 identifies a target entity with which the second communication device 712 is to exchange upcoming signaling, the target entity acting as a relay communication device. The appropriate target entity may be determined by any suitable method for device discovery in a peer-to-peer communication environment and may be, for example, another communication device such as one of third communication device 713 and fourth communication device 714 or infrastructure equipment 701. For example, the first communication device 711 may detect beacon signaling or reference signaling transmitted by one or more of the third communication device 713 and the fourth communication device 714 and/or the infrastructure equipment 702.

Prior to step R3 or as part of step R3, the first communication device 711 may communicate with one or more of the third and

fourth communication devices

713 and 714 and the infrastructure equipment 701 to determine various aspects of their capabilities and/or location according to conventional techniques. The first communication device 711 may also receive candidate target entity information from the infrastructure equipment 702, which the first communication device 711 may use to identify the target entity.

The selection of the target entity may include a process similar to that described above with respect to step T3 of the process of fig. 6. In some embodiments, the first communication device 711 polls one or more nearby communication devices to find a suitable target entity.

In the example of fig. 7, the first communication device 711 determines in step R3 that the third communication device 713 is a target entity with which the second wireless communication device 712 is to exchange upcoming signaling.

In step R4, the first communication device 711 may configure the third communication device 713 to prepare for exchanging signaling with the second communication device 712. This may include sending configuration information to the third communication device 713 to support establishing a sidelink connection between the third communication device 713 and the first communication device 711.

As part of this process, the first communication device 711 may send a resource reservation request indication to the third communication device 713 requesting that the third communication device 713 reserve radio and other resources for establishing a connection between the first communication device 711 and the third communication device 713. The resource reservation request may also include a request to establish a side link between the third communication device 713 and the second communication device 712 so that the third communication device 713 can act as a relay between the first communication device 711 and the second communication device 712.

In response, the third communication device 713 may reserve communication resources for each new sidelink and may send handover information (not shown in fig. 7) to the first communication device 711. The handover information may include an identifier (e.g., a radio network temporary identifier, RNTI) to be used by the second communication device 712 for communication with the third communication device 713 and/or a preamble to be used by the second communication device 712 as part of a random access procedure to establish a sidelink connection with the third communication device 713. The handover information additionally comprises an indication of communication resources for the sidelink between the first communication device 711 and the third communication device 713 and an indication of communication resources for the sidelink between the second communication device 712 and the third communication device 713.

The third communication device 713 may initiate a timer to control when the reserved resources may be released. If the reserved resource is not used for the corresponding side link before the end of the timer, the third communication device 713 will cancel the reserved resource, which may include enabling the resource to be used by other devices.

In step R5, the first communication device 711 transmits a handover command to the second communication device 712. The handover command may include an RRC reconfiguration message. The handover command may include an indication of the identity of the third communication device 713 serving as the target relay communication device and may be transmitted over a sidelink between the first communication device 711 and the second communication device 712 or may be routed over other network entities, for example, over a signaling exchange between each of the first communication device 711 and the second communication device 712 and the infrastructure equipment 701.

In step R6, the second communication device 712 determines that it will continue operating with the current configuration and/or will not modify its current configuration for wireless communication in accordance with the handover command in response to receiving the handover command.

Determining that it will continue operating using the current configuration may include determining that the proposed sidelink connection with the third communication device 713 is improper, or less preferred. The determination of the proposed side link connection with the third communication device 713 may use substantially the same criteria as described with respect to step T7 of the process of fig. 6.

Additionally or alternatively, the determination may include determining that the target third communication device 713 may not be suitable because it is out of range of the second communication device 712 or is not configured with a compatible radio access technology that is available with those available with the second communication device 712.

As in step T7 of the process of fig. 6, the second communication device 712 may determine an appropriate and/or preferred target device to act as a relay, such as the fourth communication device 714. Determining that the fourth communication device 714 is a more preferred or appropriate target device may be based on, for example, pre-configured preferences, radio measurements of transmissions to the fourth communication device 714, capabilities of the fourth communication device 714, and so forth.

Further, in a manner similar to that described in step T7, the second communication device 712 may additionally or alternatively identify more preferred or suitable radio resources for the sidelink connection between the second communication device 712 and the target communication device (the target device identified in the handover command, or the target device identified by the second communication device 712).

Thus, in some embodiments, determining not to change to the new configuration is in response to one or more of:

determining that communication with the third communication device 713 using the proposed sidelink is inappropriate (e.g., due to interference, listen-before-talk requirements, application level preferences, preconfigured preferences, and/or corresponding device capabilities),

-identifying alternative, preferred radio resources for communication with the third communication device 713, and

In step R7, the second communication device 712 sends a handover rejection indication to the first communication device 711 indicating to the first communication device 711 that the second communication device 712 will not modify the current configuration for wireless communication in the manner indicated by the handover command.

Accordingly, embodiments of the present technology provide a method: receiving a handover command related to a sidelink connection, determining that the proposed communication resource and/or the target relay device is not suitable or preferred, sending a handover rejection indication in response to the handover command, and refraining from implementing the configuration indicated by the handover command. The handover rejection indication may include a rejection reason indication indicating why the handover command/target radio resource has been rejected by the second communication device 712.

The first communication device 711 determines an alternate target wireless communication device to indicate association with a handover command to be subsequently sent to the second communication device 712.

As described above, the second communication device 712 can send the first communication device 711 a preferred target indication for the preferred target wireless communication device (fourth communication device 714) determined by the second communication device 712. The preferred target indication may form part of the handover reject indication or may be sent separately. In some embodiments, the handover rejection indication comprises an RRC reconfiguration message sent to the first communication device 711 via a suitable communication link, the RRC reconfiguration message comprising the preferred target indication.

The second communications device 712 may transmit an indication of the preferred target set of radio resources as described above with respect to step T8 of the process of fig. 6. The preferred target set of radio resources may be indicated as a preference for future communication via a sidelink connection with the preferred target communication device.

Accordingly, embodiments of the present technology provide a method for sending a preferred target indication and/or an indication of a preferred target set of radio resources in association with a handover rejection indication.

The first communication device 711 may thus be made aware of the target devices and/or radio resources that the second communication device 712 deems suitable, i.e. fulfilling some predetermined criteria.

In step R8, the first communication device 711 cancels the proposed handover procedure in response to receiving a handover rejection indication from the second communication device 712.

In step R9, the first communication device 711 may implicitly or explicitly indicate to the third communication device 713 that no handover procedure is to be performed. In the example of fig. 7, the cancel indication is explicit. In some embodiments, the first communication device 711 may additionally implicitly or explicitly indicate to the second communication device 712 that no handover procedure is to be conducted.

In response to the indication at step R9, the third communication device 713 may release any resources reserved in response to the indication received at step R4.

In some embodiments, the process may continue with step R2. In this subsequent iteration of this step, the first communication device 711 may determine that no handover occurred, or that handover is still needed. In the latter case, the process continues with step R3, and so on, as described above. The determination may be based on one or more of a reject cause indication, a preferred target indication and an indication of a preferred target set of radio resources and/or their presence or absence.

For example, if the rejection reason indicates that the second communication device 712 does not support the proposed frequency band, and does not receive the preferred target indication, and does not indicate the preferred target set of radio resources, the first communication device 711 may determine that there are no suitable handover candidates, and may determine not to perform a handover.

In another example, if the handover rejection indication sent by the second communication device 712 includes an indication of why the handover command/target radio resource has been rejected by the second communication device 712, the first communication device 711 may take this information into account in subsequent iterations of step R3. For example, the second communication device 712 may have indicated that the handover command was rejected because the proposed target device (third communication device 713) is outside the communication range of the second communication device 712. Thus, during subsequent iterations of step R3, the first communication device 711 may ensure that the new target wireless communication device is not the third communication device 713.

Thus, in some embodiments, the first communication device 711 may determine an alternate communication resource and/or an alternate target device to act as a relay. In the example of fig. 7, the first communication device 711 selects the fourth communication device 714 as the new target device based on its indication as the preferred target device. Thus, in step R10, the first communication device 711 sends signaling to the preferred target wireless communication device (fourth communication device 714) in a manner similar to that in step R4 described above.

Subsequently, in step R11, the first communication device 711 sends a (modified) handover command to the second communication device 712 in a similar manner as described above with respect to step R5.

Based on the modified handover command indicating that the target device is the fourth communication device 714 and determining that the indicated communication resources are appropriate and/or preferred (i.e., generally, meet the predetermined criteria), the second communication device 712 performs a handover according to the modified handover command.

Accordingly, at step R12, the communication between the first communication device 711 and the second communication device 712 continues through the sidelink connections between the first communication device 711 and the fourth communication device 714 and between the second communication device 712 and the fourth communication device 714.

In some embodiments of the present technology, the handover results in the

second communication device

612, 712 acquiring service from the target communication device. According to some embodiments, the target communication device is proposed by the second communication device but cannot communicate directly with the first communication device. To request a handover (e.g. request to reserve resources), the first communication device sends a request to the infrastructure equipment, which is able to communicate directly with the target communication device.

Fig. 8 illustrates a message sequence chart showing handover in accordance with embodiments of the present technology. In particular, the figure represents the procedures and signaling exchanges associated with a first communication device 811, a second communication device 812 and a third communication device 813 (which may be considered to correspond to the first communication device 511, the second communication device 512 and the fourth communication device 514, respectively, schematically illustrated in fig. 5). Also shown is infrastructure equipment 801 providing a cell, which may be established according to LTE/NR techniques described further herein and which may be configured to exchange signaling with one or more of the first through

third communication devices

811, 812, 813 according to some embodiments of the present disclosure.

In the example of fig. 8, the first communication device 811 determines at step S1 that a handover should occur for the existing connection 850 between the first communication device 811 and the second communication device 812.

At step S2, the first communication device 811 determines a target entity and/or target communication resource to be used for the new connection with the second communication device 812.

After steps S1 and S2, the first communication device 811 transmits a switch command 852 to the second communication device 812 at step S3.

Steps S1 to S3 may be substantially in accordance with corresponding steps of the process shown in fig. 6 and/or 7 and described above.

In response to receiving the handover command 852, at step S4, the second communication device 812 determines that the third communication device 813 is a preferred or alternative target device for handover. For example, the second communication device 812 determines that the services and/or information currently acquired from or via the first communication device 811 can be acquired from or via the third communication device 813. The second communication device 812 may determine that acquiring service and/or information via the connection to the third communication device 813 is more preferable than using the connection according to the handover command 852.

In response to the determination at step S4, the second communication device 812 transmits a handover rejection indication 854 to the first communication device in step S5. The handover rejection indication 854 comprises an indication of the identity of the third communication device 813.

In response to receiving the handover rejection indication 854, the first communication device 811 determines at step S7 that a handover should be performed in order to establish a connection between the second communication device 812 and the third communication device 813, i.e. according to the indication within the handover rejection message 854.

In some examples according to some embodiments, the first communication device 811 will send an indication to the third communication device 813 to request reservation of resources in preparation for the handover, as described above.

However, in the example of fig. 8, the first communication apparatus 811 determines at step S7 that it cannot directly communicate with the third communication apparatus 813. This may be because outside the wireless communication range of the third communication device 813 and/or because any common communication technology (or parameters) as the third communication device 813 is not supported, or for any other reason.

In response to this determination, the first communication device 811 sends a handover support request 856 to the infrastructure equipment 801 at step S8, the handover support request 856 comprising an indication of the identity of the third communication device 813. The handover support request 856 may also include an identification of the first communication device 811 and/or an indication of parameters for enabling the third communication device 813 to prepare for the handover. For example, the handover support request 856 may include the parameters contained in the resource reservation request described above with respect to step R4 of the process shown in fig. 7.

In response to the handover support request 856, the infrastructure equipment 801 sends a resource reservation request 858 to the third communication device 813 at step S9 requesting the third communication device 813 to reserve communication resources for the direct connection between the second communication device 811 and the third communication device 813. If the third communication 813 is able to support the requested handover, resources are reserved and a handover configuration message 860 is sent to the infrastructure equipment 801 at step S10. The handover configuration message 860 is forwarded by the infrastructure equipment 801 to the first communication device 811.

At step S11, in response to receiving the handover configuration message 860, the first communication device 811 sends a handover command 862 to the second communication device 812, the handover command 862 including parameters included in the handover configuration message 860, such as reserved resources, communication parameters, and the like.

In response to receiving the switch command 862, the second communication apparatus 812 performs switching and establishes a direct connection 864 with the third communication apparatus 813 at step S12.

Therefore, according to the embodiments of the present technology, even in a case where the first communication device and the third communication device (which are respective end points connected to the side link of the second communication device before and after the switching) cannot directly communicate with each other, the switching of the side link connection can be performed.

According to the above example, a first communication device (such as the first communication device 711) selects a single set of radio resources and, if applicable, a single target device to act as a relay. In some embodiments of the present disclosure, the first communication device 711 selects multiple sets of radio resources and (if applicable) one or more target devices to act as a relay, all indicated in the handover command. In some such embodiments, there may be no preparation phase (i.e., there may be no advance communication from the first communication device 711 to other infrastructure equipment and/or target devices) before sending the handover command to the second communication device 712.

In such embodiments, in response to receiving a handover command comprising multiple sets of radio resources and/or an indication of two or more target devices, a second communication device (such as second communication device 712) may select a preferred target device and/or a preferred set of radio resources based on measurements, preferences, capabilities, etc., and send the selected resources and/or the indication of the device to first communication device 711. The first communication device 711 may then proceed with the handover procedure (such as shown in fig. 6 or fig. 7, starting at step T3 or R3, respectively).

According to some embodiments, the first communication device 711 may send a sidelink initiation request to a target device (e.g., the fourth communication device 714 in step R10) selected to act as a relay, requesting the fourth communication device 714 to initiate the establishment of a sidelink connection between the fourth communication device 714 and the second communication device 712.

In some embodiments, before sending the preferred target indication in step R7, the second communication device 712 may send a resource reservation request indication to the fourth communication device 714 requesting the fourth communication device 714 to reserve appropriate resources for the sidelink connections between the first communication device 711 and the fourth communication device 714 and between the second communication device 712 and the fourth communication device 714. In other words, prior to step R7, with respect to the fourth communication device 714, the second communication device 712 may perform steps substantially corresponding to steps R3 and R4 as described above.

In such embodiments, the handover rejection indication and/or the preferred target indication may comprise an indication that a resource reservation request indication has been sent to the fourth communication device 714.

Similarly, in response to receiving the resource reservation request indication, the fourth communication device 714 may send an indication of radio resources corresponding to the reserved radio resources to the second communication device 712. Some or all of these may be indicated to the first communication device 711 as a preferred target set of radio resources.

Thus, in some embodiments, the handover rejection indication itself may substantially comprise the handover command indication. In response to receiving a handover rejection indication providing radio resources and a target device, the first communication device 711 may implement a corresponding configuration change to establish a side-link communication between the first communication device 711 and the fourth communication device 714. The first communication device 711 may indicate to the second communication device 712, either explicitly or implicitly (e.g., by not sending further handover-related signaling via the existing sidelink connection for a predetermined duration) that the corresponding configuration change is to be implemented (or has been implemented).

In some embodiments, in response to such an indication, the second communication device 712 determines that the first communication device 711 will implement or has implemented a corresponding configuration change in order to establish a side-link communication between the first communication device 711 and the fourth communication device 714. In response to the determination, the second communication device 712 may establish a sidelink connection with the fourth communication device 714 and thus an end-to-end connection with the first communication device 711 via the fourth communication device 714 acting as a relay.

In some embodiments, the preferred target device indicates a plurality of wireless communication devices. In some such embodiments, the target device indication comprises an indication of the relative preference of each indicated wireless communication device. The first communication device 711 may select a new target wireless communication device from a plurality of target wireless communication devices.

To support this determination, the first communication device 711 may measure signaling (e.g., beacon or reference signals) between itself and one or more wireless communication devices indicated in the preferred target device indication to determine that the given wireless communication device is the new target wireless communication device.

It should be appreciated that while the target wireless communication device is typically a terminal device, such as a terminal device implemented within a vehicle in a V2V or V2X scenario, in other embodiments the target wireless communication device may include infrastructure equipment that generates cells, forming part of a RAN of a wireless communication network, such as those schematically illustrated in fig. 1 and 2 (e.g., a base station, TRP, or control node). In such a scenario, the first communication device 711 may be said to switch the second communication device 712 from communicating with the first communication device 711 over a sidelink to communicating with a conventional network entity in a manner known to communications between the wireless communication device and the base station/TRP/control node in LTE and NR environments.

In some such embodiments, the end-to-end connection between the first communication device 711 and the second communication device 712 may be via one or more infrastructure equipment, rather than in a device-to-device/peer-to-peer manner.

It should also be understood that in some cases, the term 'handover' as used herein may imply that a first communication device 711 having a side-link with a second communication device 712 may cease communicating with the second communication device 712 as part of a process that facilitates the second communication device 712 communicating with a target wireless communication device. In other cases, however, the first communication device 711 and the second communication device 712 may maintain their side link communication, and the handover in this case involves establishing a further connection between the second communication device 712 and another entity. In these cases, the first communication device 711 may be considered to assist the second communication device 712 in establishing a connection to a further wireless communication device.

At step R3 and/or step R4, to facilitate establishing a connection between the second communication device 712 and a target communication device (such as the third communication device 713 or the fourth communication device 714), the first communication device 711 may request configuration information from one or more of the second communication device 712, the third communication device 713, or the fourth communication device 714, which may be communicated to one of the other communication devices to assist the second communication device 712 in establishing a sidelink connection with the target determined by the first communication device 711. This may broadly follow the method set forth for the conventional handover scenario set forth with respect to fig. 4, whereby the first infrastructure equipment and the second infrastructure equipment exchange configuration information that may be used to support handover of the communication device from the first cell to the second cell, and wherein the first infrastructure equipment may send information to the communication device to be used when connecting to the second cell.

In the example shown in fig. 7, at step R4, only a single other communication device (third communication device 713) is contacted in response to determining the target entity at step R3. However, in some embodiments, the first communication device 711 may send an indication to one or more additional entities (such as the infrastructure equipment 701) to indicate a potential handover procedure. In response, the infrastructure equipment 701 may reserve resources (i.e., avoid selecting them for transmitting data to or by communication devices in a cell controlled by the infrastructure equipment 701) to reduce subsequent interference (after handover) for the contralateral link connection or for the connection between the infrastructure equipment 701 and the communication devices served in the corresponding cell.

Accordingly, there has been disclosed a method of operating a first wireless communication device to communicate with a second wireless communication device, the method comprising transmitting to or receiving from the second wireless communication device over a wireless interface a signal representing data, the signal being transmitted or received by the second wireless communication device in accordance with a current configuration, determining that the current configuration is to be changed to a first new configuration, transmitting to the second wireless communication device over the wireless interface a first handover command, the first handover command comprising an indication that the first new configuration replaces the current configuration, and receiving from the second wireless communication device via the wireless interface a handover rejection indication, the handover rejection indication being transmitted in response to the first handover command and indicating that the second wireless communication device is to continue operating in accordance with the current configuration.

Also disclosed is a method of operating a second wireless communications device to communicate with a first wireless communications device, the method comprising: transmitting or receiving a signal representing data to or from the first wireless communication device over the wireless interface according to the current configuration; receiving a first handover command from a first wireless communication device over a wireless interface, the first handover command comprising an indication that a first new configuration replaces a current configuration; sending a handover rejection indication via the wireless interface, the handover rejection indication indicating to the first wireless communication device that the second wireless communication device is to continue operating according to the current configuration; and avoiding replacing the current configuration with the first new configuration.

Corresponding communication devices, infrastructure equipment and methods are also described, as well as circuits for communication devices and circuits for infrastructure equipment.

It should be understood that although the present disclosure has in some aspects focused on specific implementations in LTE and/or 5G based networks for providing specific examples, the same principles may be applied to other wireless telecommunication systems. Thus, even though the terms used herein are generally the same or similar to the terms of the LTE and 5G standards, the teachings are not limited to the current versions of LTE and 5G and may be equally applicable to LTE, 5G or other standards that are not based on any suitable arrangement of LTE or 5G and/or conform to any other future version.

It may be noted that the various exemplary methods discussed herein may rely on information that is predetermined/predefined in the sense that both the base station and the communication device are aware of. It will be appreciated that such predetermined/predefined information may typically be established by definition, for example in the operating standard of the wireless telecommunications system or in previously exchanged signalling between the base station and the communication device (e.g. in system information signalling), or associated with radio resource control setting signalling, or in information stored in the SIM application. That is, the particular manner in which the relevant predefined information is established and shared among the various elements of the wireless telecommunications system is not important to the principles of operation described herein. It may also be noted that the various exemplary methods discussed herein rely on information exchanged/communicated between the various elements of the wireless telecommunications system, and it will be appreciated that such communication may generally be performed according to conventional techniques, e.g., according to a particular signaling protocol and type of communication channel used, unless the context requires otherwise. That is, the particular manner in which relevant information is exchanged between the various elements of the wireless telecommunications system is not important to the principles of operation described herein.

It should be understood that the principles described herein are not only applicable to certain types of communication devices, but may be more generally applied to any type of communication device, for example, the methods are not limited to machine-type communication devices/internet of things devices or other narrowband communication devices, but may be more generally applied to any type of communication device operating, for example, using a wireless link to a communication network.

It should also be understood that the principles described herein are applicable not only to LTE-based wireless telecommunication systems, but to any type of wireless telecommunication system that supports peer-to-peer data transmission.

Further particular and preferred aspects of the invention are set out in the accompanying independent and dependent claims. It is to be understood that features of the dependent claims may be combined with features of the independent claims in combinations other than those explicitly set forth in the claims.

Accordingly, the foregoing discussion discloses and describes merely exemplary embodiments of the present invention. As will be understood by those skilled in the art, the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Accordingly, the disclosure of the present invention is intended to be illustrative, but not limiting, of the scope of the invention, as well as of the other claims. The present disclosure, including any readily discernible variants of the teachings herein, defines, in part, the scope of the foregoing claim terminology such that no inventive subject matter is dedicated to the public.

Corresponding features of the present disclosure are defined by the following numbered paragraphs:

paragraph 1. a method of operating a first communications device to communicate with a second communications device, the method comprising: sending or receiving signals representing data to or from a second communications device over the wireless interface, the signals being sent or received by the second communications device according to the current configuration; determining that the current configuration is to be changed to a first new configuration; sending a first switch command to the second communication device over the wireless interface, the first switch command including an indication that the first new configuration replaces the current configuration; and receiving a handover rejection indication from the second communication device via the wireless interface, the handover rejection indication being sent in response to the first handover command and indicating that the second communication device is to continue operating according to the current configuration.

Paragraph 2. the method of paragraph 1, wherein the first handover command includes an indication of the target set of communication resources to be used in accordance with the first new configuration.

Paragraph 3 the method of paragraph 1 or paragraph 2, wherein the signal representing the data is transmitted to or received from a first target communication device different from the first communication device according to the new configuration.

Paragraph 4. the method of any of paragraphs 1 to 3, comprising sending a second handover command in response to receiving the handover reject indication, the second handover command comprising an indication of the second new configuration.

Paragraph 5. the method of paragraph 4, wherein the handover rejection indication comprises an indication of a preferred target set of communication resources.

Paragraph 6. the method of paragraph 5, wherein, according to the second new configuration, the signal representing the data is to be transmitted or received using the preferred target set of radio resources.

Paragraph 7 the method of any of paragraphs 4 to 6, wherein the handover rejection indication comprises an indication of a preferred target communication device.

Paragraph 8 the method according to paragraph 7, wherein, according to the second new configuration, the signal representing the data is to be transmitted to or received from the preferred target communications device.

Paragraph 9 the method of paragraph 7 or 8, the method comprising sending, by the preferred target communications device, a request for communications resource allocation in response to receiving the handover rejection indication.

Paragraph 10. the method of paragraph 9, comprising: the method further comprises determining that the preferred target communication device is unable to receive signalling comprising a request for communication resource allocation sent directly from the first communication device to the preferred target communication device, and in response to determining that the preferred target communication device is unable to receive signalling comprising a request for communication resource allocation sent directly from the first communication device to the preferred target communication device, sending the request for communication resource allocation to infrastructure equipment for forwarding to the preferred target communication device.

Paragraph 11. the method of paragraph 10, comprising: receiving signalling transmitted by the infrastructure equipment indicating an indication of communications resources reserved by the preferred target communications device, wherein, in accordance with the second new configuration, signals representing data are to be transmitted to or received from the preferred target communications device using communications resources reserved by the preferred target communications device.

Paragraph 12 the method of any of paragraphs 1 to 11, wherein the signaling comprising the first handover command is sent to a device other than the second communication device for forwarding to the second communication device.

Paragraph 13 the method according to paragraph 12, wherein the device other than the first communication device is one of a third communication device and infrastructure equipment of the wireless communication network.

Paragraph 14 a method of operating a second communication device to communicate with a first communication device, the method comprising: transmitting or receiving signals representing data to or from the first communication device over the wireless interface according to the current configuration; receiving a first handover command from a first communication device over a wireless interface, the first handover command comprising an indication of a first new configuration replacing a current configuration; sending a handover rejection indication via the wireless interface, the handover rejection indication indicating to the first communication device that the second communication device is to continue operating according to the current configuration; and avoiding replacing the current configuration with the first new configuration.

Paragraph 15. the method of paragraph 14, wherein the first handover command includes an indication of the target set of communication resources to be used in accordance with the first new configuration.

Paragraph 16 the method of paragraph 14 or paragraph 15, wherein the signal representing the data is transmitted to or received from a first target communication device different from the first communication device according to the new configuration.

Paragraph 17 the method according to any of paragraphs 14 to 16, the method comprising receiving a second handover command after sending the handover rejection indication, the second handover command comprising an indication of the second new configuration.

Paragraph 18. the method of paragraph 17, wherein the handover rejection indication comprises an indication of a preferred target set of communication resources.

Paragraph 19. the method of paragraph 18, wherein according to the second new configuration, the signal representing the data is to be transmitted or received using the preferred target set of radio resources.

Paragraph 20 the method according to any of paragraphs 17 to 19, wherein the handover rejection indication comprises an indication of a preferred target communication device.

Paragraph 21. the method according to paragraph 20, wherein, according to the second new configuration, the signal representing the data is to be transmitted to or received from the preferred target communication device.

Paragraph 22 the method of any of paragraphs 14 to 21, wherein the signaling comprising the first handover command is received from a device other than the first communication device.

Paragraph 23 the method of paragraph 22, wherein the device other than the first communication device is one of a third communication device and infrastructure equipment of the wireless communication network.

Paragraph 24. a method of operating infrastructure equipment in a wireless communications network, the method comprising: receiving a handover support request from the first communication device, the handover support request comprising an indication of an identity of the third communication device; in response to receiving the handover support request, sending a resource reservation request to the third communication device; receiving a handover configuration message from the third communication device, the handover configuration message being sent in response to the handover support request and comprising an indication that the third communication device has reserved communication resources for the direct connection between the second communication device and the third communication device; and in response to receiving the handover configuration message, sending the handover configuration message to the first communication device.

Paragraph 25. the method according to paragraph 24, wherein the handover support request includes an indication of an identity of the second communication device.

Paragraph 26. a first communication device, the first communication device comprising: a transmitter configured to transmit a signal representing data to a second communication device over a wireless interface, the signal being received by the second communication device according to a current configuration; a receiver configured to receive a signal representing data, the signal being transmitted by the second communication device over the wireless interface according to the current configuration; and a controller configured to control the transmitter and the receiver such that the first communication device is operable to: the method further includes determining that the current configuration is to be changed to a first new configuration, sending a first switch command to the second communication device over the wireless interface, the first switch command including an indication of the first new configuration replacing the current configuration, and receiving a switch rejection indication from the second communication device via the wireless interface, the switch rejection indication being sent in response to the first switch command and indicating that the second communication device is to continue operating according to the current configuration.

Paragraph 27. circuitry for a first communication device, the circuitry comprising: a transmitter circuit configured to transmit a signal representing data to a second communication device over a wireless interface, the signal being received by the second communication device according to a current configuration; a receiver circuit configured to receive a signal representing data, the signal being transmitted by the second communication device over the wireless interface according to the current configuration; and a controller circuit configured to control the transmitter circuit and the receiver circuit such that the first communication device is operable to: the method further includes determining that the current configuration is to be changed to a first new configuration, sending a first switch command to the second communication device over the wireless interface, the first switch command including an indication of the first new configuration replacing the current configuration, and receiving a switch rejection indication from the second communication device via the wireless interface, the switch rejection indication being sent in response to the first switch command and indicating that the second communication device is to continue operating according to the current configuration.

Paragraph 28. a second communication device, the second communication device comprising: a transmitter configured to transmit a signal representing data to a first communication device over a wireless interface, the signal being received by the first communication device according to a current configuration; a receiver configured to receive a signal representing data, the signal being transmitted by the first communication device over the wireless interface according to the current configuration; and a controller configured to control the transmitter and the receiver such that the second communication device is operable to: the method includes receiving a first handover command from a first communication device over a wireless interface, the first handover command including an indication to replace a first new configuration of a current configuration, sending a handover rejection indication via the wireless interface, the handover rejection indication indicating to the first communication device that a second communication device is to continue operating according to the current configuration, and refraining from replacing the current configuration with the first new configuration.

Paragraph 29. circuitry for a second communication device, the circuitry comprising: a transmitter circuit configured to transmit a signal representing data to the first communication device over the wireless interface, the signal being received by the first communication device according to the current configuration; a receiver circuit configured to receive a signal representing data, the signal being transmitted by the first communication device over the wireless interface according to the current configuration; and a controller circuit configured to control the transmitter circuit and the receiver circuit such that the second communication device is operable to: the method includes receiving a first handover command from a first communication device over a wireless interface, the first handover command including an indication to replace a first new configuration of a current configuration, sending a handover rejection indication via the wireless interface, the handover rejection indication indicating to the first communication device that a second communication device is to continue operating according to the current configuration, and refraining from replacing the current configuration with the first new configuration.

Paragraph 30. infrastructure equipment for use in a wireless communications network, the infrastructure equipment providing a wireless access interface, wherein the wireless access interface is for transmitting data to and receiving data from a communications device, the infrastructure equipment comprising: a transmitter configured to transmit a signal to a communication device via a wireless access interface in a cell; a receiver configured to receive data from a communication device; and a controller configured to control the transmitter and the receiver such that the infrastructure equipment is operable to: receiving a handover support request from the first communication device, the handover support request comprising an indication of an identity of the third communication device, in response to receiving the handover support request, sending a resource reservation request to the third communication device, receiving a handover configuration message from the third communication device, the handover configuration message being sent in response to the handover support request and comprising an indication that the third communication device has reserved communication resources for a direct connection between the second communication device and the third communication device, and in response to receiving the handover configuration message, sending the handover configuration message to the first communication device.

Paragraph 31. circuitry for infrastructure equipment for use in a wireless communication network, the infrastructure equipment providing a wireless access interface, the circuitry comprising: a transmitter circuit configured to transmit a signal to a communication device via a wireless access interface in a cell; a receiver circuit configured to receive data from a communication device; and a controller circuit configured to control the transmitter circuit and the receiver circuit such that the infrastructure equipment is operable to: receiving a handover support request from the first communication device, the handover support request comprising an indication of an identity of the third communication device, in response to receiving the handover support request, sending a resource reservation request to the third communication device, receiving a handover configuration message from the third communication device, the handover configuration message being sent in response to the handover support request and comprising an indication that the third communication device has reserved communication resources for a direct connection between the second communication device and the third communication device, and in response to receiving the handover configuration message, sending the handover configuration message to the first communication device.

Reference to the literature

[1]Holma H.and Toskala A,“LTE for UMTS OFDMA and SC-FDMA based radio access”,John Wiley and Sons,2009.

[2]R2-133840,“CSMA/CA based resource selection”,San Francisco,USA,November 2013

[3]3GPP TR 38.885“Study on NR Vehicle-to-Everything(V2X)”

Claims

1. A method of operating a first communications device to communicate with a second communications device, the method comprising:

transmitting or receiving signals representing data to or from the second communication device over a wireless interface, the signals being transmitted or received by the second communication device according to a current configuration,

determining that the current configuration is to be changed to a first new configuration,

sending a first handover command to the second communication device over the wireless interface, the first handover command comprising an indication that the first new configuration replaces the current configuration, and

receiving a handover rejection indication from the second communication device via the wireless interface, the handover rejection indication sent in response to the first handover command and indicating that the second communication device is to continue operating in accordance with the current configuration.

2. The method of claim 1, wherein the first handover command comprises an indication of a target set of communication resources to be used in accordance with the first new configuration.

3. The method of claim 1, wherein, in accordance with the new configuration, the signal representing the data is transmitted to or received from a first target communications device different from the first communications device.

4. The method of claim 1, the method comprising:

sending a second handover command in response to receiving the handover rejection indication, the second handover command comprising an indication of a second new configuration.

5. The method of claim 4, wherein the handover rejection indication comprises an indication of a preferred target set of communication resources.

6. The method of claim 5 wherein, in accordance with the second new configuration, the signal representing the data is to be transmitted or received using a preferred target set of radio resources.

7. The method of claim 4, wherein the handover rejection indication comprises an indication that a target communication device is preferred.

8. The method of claim 7 wherein, in accordance with the second new configuration, signals representing the data are to be transmitted to or received from the preferred target communications device.

9. The method of claim 7, the method comprising:

sending, by the preferred target communications device, a request for communications resource allocation in response to receiving the handover rejection indication.

10. The method of claim 9, the method comprising:

determining that the preferred target communications device is unable to receive signalling comprising a request for communication resource allocation sent directly from the first communications device to the preferred target communications device, an

In response to determining that the preferred target communication device cannot receive signaling comprising the request for communication resource allocation sent directly from the first communication device to the preferred target communication device, sending the request for communication resource allocation to infrastructure equipment for forwarding to the preferred target communication device.

11. The method of claim 10, the method comprising:

receiving signaling sent by the infrastructure equipment indicating an indication of communication resources reserved by the preferred target communication device, wherein

In accordance with the second new configuration, signals representing the data will be transmitted to or received from the preferred target communications device using communications resources reserved by the preferred target communications device.

12. The method of claim 1, wherein signaling comprising the first handover command is sent to a device other than the second communication device for forwarding to the second communication device.

13. The method of claim 12, wherein the device other than the first communication device is one of a third communication device and infrastructure equipment of a wireless communication network.

14. A method of operating a second communications device to communicate with a first communications device, the method comprising:

transmitting or receiving signals representing data to or from the first communication device over a wireless interface according to a current configuration,

receiving a first handover command from the first communication device over the wireless interface, the first handover command comprising an indication of a first new configuration replacing the current configuration,

sending a handover rejection indication via the wireless interface, the handover rejection indication indicating to the first communication device that the second communication device is to continue operating according to the current configuration, and

refraining from replacing the current configuration with the first new configuration.

15. The method of claim 14, wherein the first handover command comprises an indication of a target set of communication resources to be used in accordance with the first new configuration.

16. The method of claim 14, wherein, in accordance with the new configuration, the signal representing the data is transmitted to or received from a first target communications device different from the first communications device.

17. The method of claim 14, the method comprising:

after sending the handover rejection indication, receiving a second handover command, the second handover command comprising an indication of a second new configuration.

18. The method of claim 17, wherein the handover rejection indication comprises an indication of a preferred target set of communication resources.

19. The method of claim 18 wherein, in accordance with the second new configuration, the signal representing the data is to be transmitted or received using a preferred target set of radio resources.

20. The method of claim 17, wherein the handover rejection indication comprises an indication that a target communication device is preferred.

21. The method of claim 20 wherein, in accordance with the second new configuration, signals representing the data are to be transmitted to or received from the preferred target communications device.

22. The method of claim 14, wherein the signaling comprising the first handover command is received from a device other than the first communication device.

23. The method of claim 22, wherein the device other than the first communication device is one of a third communication device and infrastructure equipment of a wireless communication network.

24. A method of operating infrastructure equipment in a wireless communications network, the method comprising:

receiving a handover support request from the first communication device, the handover support request comprising an indication of an identity of the third communication device,

transmitting a resource reservation request to the third communication device in response to receiving the handover support request,

receiving a handover configuration message from the third communication device, the handover configuration message being sent in response to the handover support request and comprising an indication that the third communication device has reserved communication resources for a direct connection between a second communication device and the third communication device, and

in response to receiving the handover configuration message, sending the handover configuration message to the first communication device.

25. The method of claim 24, wherein the handover support request comprises an indication of an identity of the second communication device.

26. A first communication device, the first communication device comprising:

a transmitter configured to transmit a signal representing data to a second communication device over a wireless interface, the signal being received by the second communication device according to a current configuration,

a receiver configured to receive a signal representing data, the signal being transmitted by the second communication device over the wireless interface according to the current configuration, an

A controller configured to control the transmitter and the receiver such that the first communication device is operable to:

sending a first handover command to the second communication device over the wireless interface, the first handover command comprising an indication of the first new configuration replacing the current configuration, and

27. Circuitry for a first communication device, the circuitry comprising:

a transmitter circuit configured to transmit a signal representing data to a second communication device over a wireless interface, the signal being received by the second communication device according to a current configuration,

a receiver circuit configured to receive a signal representing data, the signal being transmitted by the second communication device over the wireless interface according to the current configuration, an

A controller circuit configured to control the transmitter circuit and the receiver circuit such that the first communication device is operable to:

28. A second communication device, the second communication device comprising:

a transmitter configured to transmit a signal representing data to a first communication device over a wireless interface, the signal being received by the first communication device according to a current configuration,

a receiver configured to receive a signal representing data, the signal being transmitted by the first communication device over the wireless interface according to the current configuration, an

A controller configured to control the transmitter and the receiver such that the second communication device is operable to:

29. Circuitry for a second communications device, the circuitry comprising:

a transmitter circuit configured to transmit a signal representing data to a first communication device over a wireless interface, the signal received by the first communication device according to a current configuration,

a receiver circuit configured to receive a signal representing data, the signal being transmitted by the first communication device over the wireless interface according to the current configuration, an

A controller circuit configured to control the transmitter circuit and the receiver circuit such that the second communication device is operable to:

30. Infrastructure equipment for use in a wireless communications network, the infrastructure equipment providing a wireless access interface for transmitting data to and receiving data from a communications device, the infrastructure equipment comprising:

a transmitter configured to transmit a signal to a communication device via the wireless access interface in a cell,

a receiver configured to receive data from the communication device, an

A controller configured to control the transmitter and the receiver such that the infrastructure equipment is operable to:

31. Circuitry for infrastructure equipment for use in a wireless communications network, the infrastructure equipment providing a wireless access interface, the circuitry comprising:

a transmitter circuit configured to transmit a signal to a communication device via the wireless access interface in a cell,

a receiver circuit configured to receive data from the communication device, an

A controller circuit configured to control the transmitter circuit and the receiver circuit such that the infrastructure equipment is operable to: